Fix #3068 (condition_variable deadlock) #3100
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hkaiser
reviewed
Jan 14, 2018
hpx/util/unlock_guard.hpp
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| @@ -12,6 +12,8 @@ | |||
| /////////////////////////////////////////////////////////////////////////////// | |||
| namespace hpx { namespace util | |||
| { | |||
| struct already_unlocked_t {}; | |||
| constexpr already_unlocked_t already_unlocked = already_unlocked_t{}; | |||
| /////////////////////////////////////////////////////////////////////////// | |||
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Is this type used anywhere? AFAICS, the newly added constructor unlock_guard(Mutex& m, already_unlocked_t) are not called from anywhere.
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Sorry. I at first misread the paper and thought we needed it. It is indeed not used anywhere.
hkaiser
reviewed
Jan 14, 2018
| //The following ensures that the inner lock will be unlocked | ||
| //before the outer to avoid deadlock (fixes issue #3608) | ||
| std::lock_guard <std::unique_lock<mutex_type> > unlock_next | ||
| (l, std::adopt_lock); |
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TenGumis
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Jan 14, 2018
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According o @K-ballo, condition_variable_any has even more problems, and condition_variable unnecessarily duplicates its functionality, but this should fix the deadlock bug described in #3068 by alternating the order of destructors.